say tamerlan tsarnaev and his younger brother dzhokhar bombed the boston marathon. and another, a police officer, died thursday. mourners gathered to remember one of them--29- year-old krystle campbell-- monday.with a salute to the young woman who loved to watch the runners cross the bombing victims remain in the hospital, where doctors say amputees are beginning to learn to walk again. "it takes a lot of safety, a have to learn new routines." surviving suspect 19-year- old dzhokhar tsarnaev is also hospitalized. he is charged in federal court destruction and malicious destruction of property shaw resulting in death. questions are piling up about his brother's activities--the fbi investigated tamerlan in 2011 at the request of russia, tamerlan then went in 2012. "was there any procedure for the fbi to follow up on the activities of somebody over effectively been cleared?" monday afternoon, the fbi turned boylston street-- site of the bombings--back over to the city of boston. the mayor received an american flag that flew over the marathon finish line.marking schmidt, reporting.